An electronic design layout, such as for an integrated circuit or printed circuit board, includes many substrate layers. Part of an electronic design's development process is to simulate the electronic design while taking into account the electronic design's layout. Some layers are “conductor” layers that include metal tracks for coupling portions of the electronic design, while other layers are “insulation” layers that isolate the conductor layers from each other. “Metal fills” are included on an electronic design layout in order to mitigate the impact of chemical mechanical polishing (CMP) on the insulation layers during device fabrication by prohibiting the CMP from etching too much into an insulation layer.